The invention relates to power transmission belts having a low cordline and a method of producing same.
It is known in the art to make power transmission belts from elastomeric materials having an embedded tensile member. The belts may describe a multi-rib, toothed or v type profile. The belts run in pulleys having a cooperating profile.
It is known that the tensile cord in power transmission belts is generally disposed in an elastomeric matrix. In particular, on multi-ribbed belts the tensile members are disposed in the body of the belt. This form of construction places an increased lever arm on the belt rib which is supported by the tensile members. The amount of force exerted is in direct proportion to the radial distance from the center of the tensile cord line to the bearing surface of the mating pulley. A longer lever arm length diminishes the operating life of the belt.
The method of fabrication of the belt determines, in part, the location of the tensile cord. In the case of ground belts, a belt slab is molded and vulcanized on a mandrel. The belt slab is then removed and the multi-rib profile is then ground into the belt slab. Since the grinding operation cannot be completely controlled, some allowance must be made in the location of the tensile cord to prevent it from being cut by the grinding operation. This results in the tensile cord line being a larger than preferred distance from a rib apex.
Representative of the art is U.S. Pat. No. 3,820,409 to Meadows which discloses a v-belt having a plurality of closely spaced supporting cords arranged transverse to and on at least one side of the load carrying cord.
What is needed is a belt having a significantly reduced distance from a tensile cord to a rib apex. What is needed is a belt having a significantly reduced distance from a tensile cord to a rib/pulley interface. What is needed is a belt having an overcord layer disposed in an elastomeric layer overlying a tensile cord for controlling a tensile cord location during molding. The present invention meets these needs.
The primary aspect of the invention is to provide a power transmission belt having a significantly reduced distance from tensile cord to a rib apex.
Another aspect of the invention is to provide a power transmission belt having a significantly reduced distance from a tensile cord to a rib/pulley interface.
Another aspect of the invention is to provide a power transmission belt having an overcord layer disposed in an elastomeric layer overlying a tensile cord for controlling a tensile cord location during molding.
Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings.
The invention comprises a belt having a plied construction overlying tensile cords. An elastomeric layer overlies an overcord which overlies yet another elastomeric layer which in turn overlies a tensile cord. The overcord layer supports the tensile cords during molding thereby stabilizing a cordline position. This construction results in a significantly reduced distance from a tensile cord centerline to a rib apex and rib/pulley interface in a multi-ribbed belt.